Traditional systems and methods for bending wood involved complex systems of clamps and/or forms. For example, in U.S. Pat. No. 4,771,281 a curved wood bending machine is disclosed for bending solid, veneered or laminated wooden members. The machine has a support frame with a generally planar top member on which a plurality of guide rails are connected in predetermined circumferential relationship and radial planes from a common counterpoint on the top member. Clamping assemblies are slidably mounted on the guide rails and can be moved on the guide rails to predetermined positions relative each other. The clamping assemblies have a fixed vertical shoe and a coacting movable shoe which is activated by a pneumatically operated cylinder and plunger arrangement so that a desired curvature can be established to fit and bend an elongated wooden member therein. Locking members to prevent accidental movement of the clamping assemblies after they are set for the predetermined shape for bending the wooden member.
Similarly, U.S. Pat. No. 6,330,894 discloses a form, a jig, for bending wood. The jig disclosed in this patent is particularly advantageous for bending wood in the construction of custom spiral staircases. The jig comprises a trunk and multiple arms. Each of the arms has an inner end portion releasably attached to the trunk and an outer arm portion adapted to removably attach the wooden board thereto. When the wooden board is attached to the outer end portions of the arms, the wooden board is bent to conform to a curve defined by the end portions of the arms as it extends up, and around the trunk. The trunk and arms are preferably cylindrical tubes. The arm portions that attach to the trunk are split cylinders that may be locked on the trunk with a bolt. Each arm includes an inner cylindrical tube which slides within an outer cylindrical tube so that the outer end portion of the arm may be locked at a selected radius from the trunk so that the jig may be used to bend boards at varying radiuses.
The use a hot mandrel to assist in the bending of wood is more than a century old. As described in U.S. Pat. No. 186,779, hot air or steam, is passed through a pip (mold) to heat it up. A piece of wood, e.g., an umbrella stick, that is already in a softened and moist condition, is passed in between a series of clamps. Levers are used to moved and firmly hold and bend the wood around the mold. The heat of the mold dries the wood thoroughly and cures the same by softening the resinous materials in the wood. This allows the compressed fibers to rearrange themselves, so that when the curing operation is completed the bent wood is firmly set in its shape.
Despite this general knowledge, there is a need for improved and enhanced production processes and systems for bending wood and these are now provided by the present invention.